Automatic circuit maker and breaker



April 14, 1925.

H. N. SHAW AUTOMATIC CIRCUIT MAKER AND BREAKER Filed May 8, 1922 INVENTOR.

+ ATTORNEYS.

Patented Apr. 14, 1925,

PATENT OFFICE.

HAROLD n, SHAW, OE MILWAUKEE, WISCONSIN.

AUTOMATIC CIRCUIT MAKER AND BREAKER.

Application filed May 8, 1922. Serial Nov 559,321.

To aZZ whom it may concern:

Be it known that I, HAROLD N. SHAw, a citizen of the ljinited States, and resident of Milwaukee, in the county of Milwaukee and State of Wisconsin, have invented new and useful Improvements in Automatic Circuit Makers and Breakers, of which the following is a description, reference being had to the accompanying drawings, which are a part of this specification.

This invention relates to automatic circuit makers and breakers and has for its object to provide an automatic electro-magnetic switch which may be effectively employed for controlling electrical circuits of various kinds, such for example as the circuit of an electric heating device, whereby the temperature thereof may bemaintained substantially constant. I i

A further object of the invention is to provide a device of the class described which may be operated by the changes or variations in the current taken by the heating element as its temperature varies.

A still further object of the invention is to provide a device of the character described which is simple in construction,

comparatively inexpensive to manufacture,

and more efiicient in use thanthose which have been heretofore proposed, and which is entirely independent of the heating device or other apparatus with which it may be employed.

\Vith these and other objects in view, the

invention consists in the novel details of construction, and combinations of parts more fully hereinafter disclosed and particularly pointed out in the claims,

In the accompanying drawings in which like numerals designate like parts in all the views;

Figure 1 is a top plan view of an electromagnetic switch madein accordance with the present invention, a portion of the cover plate and certain other parts being. broken away for the sake of clearness;

Fig. 2 is a transverse sectional view taken approximately on the plane indicated by the line 2-2 of Fig. 1, looking in the direction of the arrows;

Fig. 3 is a fragmentary cross sectional view through one pair of contact members, taken approximately on the plane indicated by the line 83 of Fig. 1;

Fig. 1 is a wiring diagram illustrating the connections between the switch shown in Figs. 1 and 2 and a plurality of resistance heating coils such as are commonly employed in an electrical heating apparatus; and i Fig. 5 is a'digrammatic plan view of a sli htly modified form of the invention.

Referring more especially to Figs. 1 and 2 the numeral 10 indicates a frame which is preferably composed of a plurality of laminations or metallic sheets 11, which preferably takes the form of a hollow square as seen in plan. The inner sides of the said square are provided with the pairs of 0ppositely disposed projections 12 and 13, constituting pole pieces which are adapted to receive the coils or windings l4 and 15 respectively, as will be clear from Fig. 1. The said laminations are provided on their tops and bottoms with the heavier strengthening members 17 all of the said laminations as well as the said members 17 are closely compacted and securely welded to the tubular supporting members 18.

One pair of the said members 18 has secured to its topgand bottom ends respectively, the transversely extending bearing members 19 and 20, which are secured to the said supporting members 18 by means of the vertically extending bolts 21 passing through the bores of the said members 18, as will be clear from Fig. 2. The bearing members 19 and 20 are centrally drilled to provide bearings for the shaft 22, which shaft carries an armature 23 composed of a 1;)lurality of laminations built up and secured to the said shaft by welding, or in any other suitable manner, similar to the construction described in connection with the field member 10. I

The said armature is of a diameter slightly less than the distance between the opposing field poles, 12 and 13, in order to provide a small air gap as is usual in this class of apparatus and the said armature is of a width sufficient to a little more than bridge the angular gap between two adjacent field poles.

The arcuate faces of the armature have secured to them by welding, or in any other suitable manner, the stop members 24 of a width slightly less than the angular dis taucc between two adjacent field poles, as

will be clear from Fig. 1. The said stop members 21 are thus adapted to oscillate between adjacent lields and to engage the. side faces thereof, in order to limit the movement of the armati'ire, as will presently appear.

The shaft has 'rigidly secured to it adjacent the t 'ansv'erse bearing member 19, an arm 25 of suitable insulating material. The said arm 5 is provided with a pair of oppositely disposed metallic contact members 26 and 27, preferably set flush with the surfaces of the said arm in suitable recesses provided therein. and retained in place by means of the screws or othe' fastenings 2S and 21) respectively.

The said contact menibcrs 26 and 27 are adapted to more with the said arm 25 and shaft 223 to engage a pair of relatively stationary contact members 30 and 31, secured to and insulated from the bearing arm or member 19 by means of the clips 32 and 33 and. the bolts or sore ill: and The said contact members 30 and 31. preferably comprise a plurality of wires placed adjacent one another and soldered. together, the ends of which are bent upwardly as at 2-56, see 1? 3.

This construction provides an inexpensive yet e' lent resilient contact member which has been found to answer all the requirements for this type of device. The bend 37 in the said conta "t members 31 is adapted to engage the top surface of the movable rontact carrying arm and the contacts 126 and 27 carried thereby, willv be readily apparent.

In the particular form of the device herein illustrated, the coils 15 are preferably formed in three separate and distinct parts indicated by the numerals TD, ll and 42.

its above stated, the switch is especially adapted for use in connection with electric heating elements for the purpose of automatically controlling their ten'iperature. l n .l l tlj. il there is diagrannnaticull v illustrated a heating; cicn'ieut comprising the tour rcsislance coils 51, 52, 52), and ln order to control this said heating element by means of the switch constituting the present invention the coils 14; of the said switch are connected in series with the resistance coil 51. The coils 40 are connected in series with the resistance element 52, the coils ll are likewise connected in series with the resistance elen'ient 58, and the coils 42 are connected with the resistance element 51.

One end of the coils 4L0 is connected to one end of the coils 1:1. by means of a wire and one end of the resistance element 53 is connected to one end of the resistance element by means of a wire 56.

The wire 57 leads from one end of the coils Lil. to a resistance element or coil the. other end of which is connected to the main supply lead 59, as will be readily understood. A shunt circuit. 60, including: a switch 61 may be provided for cutting out the resistance 58 under certain conditions or when desired. The other main lead wire 62 is connected to the other end of the resistance coil 51, as will be readily uiulerstood, and it is also connected by means of a Wire 63 to one end of the resistance element 52.

The contact members 27 and 31 of the automatic switch above described are connected by means of wires 6-1; and (35, res pro tively, to the lead wire 62 and the wire 50. as will be clear from Fig. 4. In like manner the contact members and 30 of the said switch are connected resp etively by the wires 66 and 67 to the wires 59 and One end of the coils 4-2 is connected by the wire 68 to the return lead 5i) in order to complete its work.

The operation of the device is as follows:

Supposing; the resistance element to be cold, the switches open and the power iusl turned on, the current will pass from line (32 to and through the resistance coil 51, coils 14L- of the automatic switch, along wire 57, through resistance 58 to the return wire 5!). The current will also pass from the said wire 62 by way of wire 63 through the re sistance coil 52, coils 40 of the automatic switch, Wire 55, to and through coils l1 o lhe said switch, thence through the resist ance element or coil 53, along wire 56 to and through resistance coil 5a, then through coils T2 of the switch and along wire {58 to the return wire or lead 59.

Under these conditions the coils 14L exert a much weaker magnetic influence than. do the coils e0, ll, and 42 of the field elements 15, thereby causing the rotor or armature 2?. to move in a clock-wise direction, as seen in Fig. 1. This n'iovement of the said armature is, of course, transmitted throiuzjh (hev shaft 2 to the contact carrying arm 32.), thereby causing the contacts 26 and 2'? lo move under and. engage with the. slal ion-ary contacts 30 and 31.

Before the closing of l hesc switches, it will be noted that the resistance coils 52, 5 3 and 5st and the coils 40, 1-1 and s2 of the auto matic switch were all eonnerted in series. However, when the switch contacts 26, 30, 27, and 31 are thus closed, the coupling of the above mentioned coils is changed from series to parallel, thereby changing the di rection of the current flow through the resistance coil and the coils ll. of the automatic switch.

The field coils l0, ll. and 42 of the switch are so wound and connected that when they are coupled and actuated in series, as above disclosed, their n'iagnctic etl'ect is cumulative; in other words with the current flowing through the coils, when connected in scries,-they all tend to produce one polarity on the upper field pole, and the opposite polarity on theopposite field pole.

However, when the coupling is changed from series to parallel, the direction of the current flowing through the coils 11 isreversed, thereby reversing the polarity thereof, and consequently weakening the magnetic strength of the field poles 13.

V7 hen the switches are opened and the various'coils 52, 53, 54, 40, all, and 42 are connected in series, a certain amount of current fiowsthrough all of the coils and a certain pull is exerted upon the rotor or armature 23. Supposing, for example, that this current be one ampere, when the coils are connected in series, when the coupling is changed to parallel by the closing of the switch contacts 26 and 30, and 27 and 31, a current of three amperes will flow through each section or nine amperes in all, and only one of the coils 4O, 11, or 42 would be effective, inasmuch as the other two oppose and neutralize each other.

However, since three times the amount of current is flowing through the effective turns, the pull upon the rotor or armature 23 does not changeand the said armature keeps moving until the stop members 2i engage with the pole pieces 13 and the contacts 26 and 80, and 27 and 31 are fully closed.

The heating element comprising the coils 51, 52, 53, and 5% will now heat up rapidly and when the desired maximum temperature is reached the coils 15 become weaker than the coils 14, thereby causing the rotor to move in a counter clockwise direction and opening the switch contacts 26 and 30, and 27 and 31. As the temperature of the heating element falls, the coils 15 again become stronger, with the result that the switch contacts are again closed, thus coupling the resistance elements in parallel instead of in series with a consequent increase in the current consumed and the amount of heat given oil".

It will. thus be seen. that this switch will automatically maintain a substantially constant temperature within certain limits, inasmuch as whenever the temperature rises to a desired maximum, the resistance coils will be connected in series, thus reducing the amount of heat generated, and whenever the temperature falls to a predetermined minimum they will automatically be connected in parallel, thereby increasing the current consumed and the amount of heat given off.

The resistance coils 52, 53, and 54; of the heating device are preferably composed of a material having a suitable temperature coeiiicient of resistance, i. e. the resistance thereof changes with their temperature in a certain determined amount. On the other hand the resistance coil 51 is preferably composed of a material having a tempera-- ture coeflicient ofresistance of substantially zero. In this way the magnetic effect oi? the field coils 14 of the switch may be maintained substantially constant, while that of the field coils 15 maybe made to vary, as above disclosed, depending upon the temperature of the said coils 52, 53, and 5 1. In one form of heating device, the said coils 52, v53, and 5 1 may be made of a nickel rib bon which has a certain predetermined temperature coefficient of resistance and which is suitable for a particular class of the work.

In Fig. 5 there is shown a slightly modified form of the automatic switch in which the rotor or armature stampings may be so shaped as to provide integral stop members adapted to' engage the pole pieces of the field coils.

This construction is particularly adapted for use with an alternating current shunt coil control device and its operation is substantially the same as that above describeijl in connection with the form shown in Figs. 1, 2, and 3, which form is more especially adapted for use with a direct current.

However, when the switch is used with an alternating current or transformer type of heating element, the coils 1 1 should be replaced by shunt coils and the pole'faces shaped substantially as shown in Fig. 5 so as to have a variable gap.

,It is necessary with this type of switch that the movable switch member be actuated relatively quickly one way or the other in order to prevent destructive arcing between the contacts. This is accomplished by the stop pieces 24 because as they leave the poles with which they have been in contact, their attraction falls off and this force is available for the acceleration of the rotor.

It is obvious that those skilled in the art may vary the details of construction, as well as the arrangement of parts without depart ing from the spirit of the invention, and therefore it is not wished to be limited to the above disclosure, except as may be required by the claims.

lVhat is claimed is:

1. An automatic circuit controlling device comprising a plurah'ty of contact members; and means responsive to variations in the resistance of an electric circuit, for controlling said contact members.

2. An automatic circuit controlling device comprising a plurality of contact members adapted to be included in an electric circuit; and means also included in said circuit and responsive to changes in the resistance thereof, for controlling said contact members. i

3. An automatic temperature controlling device comprising a plurality of contact members adapted to be included an electric circuit with a resistance heating element; and magnetic -means also included in said circuit and responsive to variations in the resistance thereof, for controlling said contact members.

l. In an automatic switch the combina tion of a relatively stationary lield member; a movable armature member; contacts carried by said field member; additional contacts carried by said armature member, for engagen'ient with said field-carried contacts; and windings carried by said field member, responsive to changes in the resistance of an electric circuit, for controlling the movements of said armature.

In an automatic switch. the combination of a relatively stationary field member; a movable armature member; stops carried by said armature for limiting its movement; contacts carried by said lield member; additional contacts carried by said armature member, for engagement with said fieldcarried contacts; and windings carried by said field member, responsive to changes in the resistance of an electric circuit, for controlling the movei'nents of said armature.

6. An automatic switch for controlling the temperature of an electric heating element comprising a field frame having a plurality of pairs of oppositely disposed pole members; a shaft rotatably mounted in said frame; an armature carried by said shaft; a plurality of pairs of contact mem bers carried by said frame and armature, for making and breaking circuit; windings upon one pair of said field pole members adapted to produce a substantially constant magneto motive force therein; additional windings upon another pair of said pole members for producing a magneto motive force therein; and connections between said contact members and the said last mentioned windings, whereby the effective magneto motive force produced by the latter will be the same with either series or parallel connections, but will vary with the temperature of the heating element.

7. In an automatic switch the combination of a relatively stationary lield member; a movable armature member; stops carried by said armature for limiting its movement; contacts formed of a plurality of parts carried by said licld member; additional contacts carried by said armature member, for engagement with said lield-- carried contacts; and windings carried by said field member, responsive to changes in the resistance of an electric circuit, for controlling the movements of said armature.

8. An automatic switch having salient lield poles and a rotor so shaped that as the latter moves the magnetic flux changes at a constant rate in the case of series coils. and the magneto motive force changes il a constant rate in case of alternating cur rent shunt coils.

In testimony whereof, I allia my signature.

HAROLD N. SHAlV. 

